Pneumatic marking device

ABSTRACT

A tool pneumatically operable under the control of an operator to prick a piece of work, such as a bolt head or stud, in rapid succession with a group of marks to indicate a torqued condition of the work. The tool has a socket to be placed over the work; and has an operator controlled throttle for applying operating air to mechanism for marking the work.

United States atent Related US. Application Data iii 4*; a it 12 0 Lesner Nov. 27, 1973 [54] PNEUMATIC MARKING DEVICE 2,883,927 4/1959 Egbert 101/4 Inventor: Richard s. Lesner, ntia Mich. 3,523,471 8/1970 Lance 8l/52.5 {73.1w .xgffi ncwcflgzimedmir TEICdiiPany FOREIGN PATENTS OR APPLICATIONS I l e K! 0 New York N'Y. 1,179,130 1/1970 Great Britain 30/362 [22] Fil d; D 14, 1971 Primary Examiner-James L. Jones, Jr.

Att0rneyStephen J. Rudy [21] Appl. No.: 207,824

[57 ABSTRACT A tool pneumatically operable under the control of an operator to prick a piece of work, such as a bolt head or stud, in rapid succession with a group of marks to indicate a torqued condition of the work. The tool has a socket to be placed over the work; and has an operator controlled throttle for applying operating air to mechanism for marking the work.

3 Claims, 5 Drawing Figures PMENIEU NOV 2 7 I973 SHEET 16F 2 PNEUMATIC MARKING DEVICE This application is a division of original application, Ser. No. 44,417, filed June 8, 1970, now US. Pat. No. 3,661,040 dated May 9, 1972.

BACKGROUND OF THE INVENTION This invention is directed to a tool embodying pneumatically operable work marking mechanism.

The general objective of a tool of this nature is to apply a group of visible marks to the work, such as the head of a bolt or stud, to indicate to those concerned that the work has been tightened to a predetermined degree of tightness. This provides a desirable advantage in that it facilitates inspection procedures in determining whether the work has received the proper torque.

A feature of the invention is a locating plunger which is operable to bring a marking rod into contact with the work regardless of the extent to which the work extends axially into the work socket.

Another feature lies in the provision of a reciprocating piston hammer adapted to repeatedly pound the marking rod in an arrangement in which the marking rod is adapted under such action to oscillate from side to side and simultaneously turn on its axis so as to impart in rapid succession a group of clearly visible marks to the head of the work.

In a first embodiment of the invention, the marking mechanism is illustrated as incorporated in the housing of a nutrunner. In this form, the marking mechanism is adapted to be operated automatically following final torque delivery. It is also illustrated in a second embodiment as a unit separate from the nutrunner. In this latter form, operation of the marking mechanism is manually controlled and may be selectively applied by the operator to the work. As a separate unit, the marking mechanism may be located externally of the nutrunner; it may also be associated with other machines.

BRIEF DESCRIPTION OF THE DRAWING In the accompanying drawing:

FIG. 1 is an elevational view, partly in section, of a pneumatic nutrunner embodying the marking mechanism of the present invention;

FIG. 2 is a schematic showing of the relation of the shut-off valve to the cam release clutch;

FIG. 3 is a detail section of the marking mechanism, drawn to an enlarged scale for added clarity;

FIG. 4 is a plan view of the head of a threaded fastener which has been subjected to the marking action of the marking mechanism; and

FIG. 5 is a second embodiment in which the marking mechanism is arranged as a separate unit for use as a tool apart from the nutrunner.

DESCRIPTION OF A FIRST EMBODIMENT Reference is now directed to FIGS. 1-4 of the draw ing in which is shown a pneumatic nutrunner having a general housing 11 defined by a succession of sections connected to one another in end-to-end relation. An angle head housing section 12 is detachably coupled at the end of its long arm 13 to the general housing of the tool, as at 14. A shorter arm 15 of the angle head extends at an angle to the general housing; it supports a drive shaft 16 carrying a work socket 17 adapted for driving engagement with a threaded fastener, such as the nut 18 which is to be threadedly tightened upon the stud 19..

An inlet 21 at the rear of the tool is connectible to a source of pressure air. Operation of a throttle valve 22 in the tool allows flow of inlet air through a normally open shut-off valve 23 to drive a rotary air motor at 24 of a conventional slidable vane type. The motor is drivingly connected in conventional manner through a torque release cam clutch 25 (FIG. 2) with an output spindle 26. The latter extends into the long arm 13 of the angle head; and is drivingly connected by means of a bevel gear 27 with a gear 28 splined to shaft 16. Gear 28 is supported in a bearing 29.

The clutch includes a driving member 31 with which an axially disengageable clutch member 32 is normally held engaged under the force of a clutch return spring 33. The shut-off valve 23 is in the form of a disc which is guided to and from a valve seat 35 by means of a valve stem 36, the latter being slidable in a bore of a guide bushing 37. A slide rod 38, having one end abutting the disengageable clutch member and having its other end abutting the valve stem, normally holds the shut-off valve in an open condition, as in FIGS. 1 and 2, during the time that the clutch is engaged.

When the nut 18 has been tightened upon the stud 19 to a preset degree, clutch member 32 is forced by the torque reaction axially away from the driving clutch member 31 against the force of the clutch spring 33. The slide rod 38, under force of inlet air supplemented by the force of a spring 39 acting upon the head of the shut-off valve, follows the disengaging clutch member until the valve closes upon its seat. The inlet air is thus shut off from the motor causing the latter to stop. The clutch, however, remains held by the rod in its disengaged condition under pressure of inlet air acting over the seated shut-off valve. This condition will continue until the operator releases the throttle valve 22 to closed condition. A nutrunning tool of the foregoing general construction and mode of operation is described in detail in US. Pat. Nos. 3,298,481 and 3,187,860.

In the present embodiment, the drive shaft 16 has been improved to serve not only as a drive shaft for the nutrunner but also as a housing for metal marking mechanism 40 (FIGS. 1 and 3); and the shut-off valve 23 has been modified so that following shut-off of inlet air to the motor a restricted volume of inlet will automatically be diverted to operate the marking mechanism. Inlet air pressure over the head of the shut-off valve 23 remains adequate to hold the valve closed despite the restricted air volume being diverted to the marking mechanism.

As the shut-off valve is seated, a passage 41 in its stem connects with ports 42 in the guide bushing 37 so as to allow inlet air to pass through the valve stem to a housing port 44. The latter port connects by means of an external flexible hose line 45 with a port 46 leading into the marking mechanism. When the shut-off valve is in its open condition, as in FIG. 1, communication of the inlet 21 through the ports leading to the hose 45 is blocked.

The drive shaft 16 is shown here as extending at right angles to the longitudinal axis of the general housing of the tool. It comprises a pair of hollow cylindrical sections 47 and 48 which are threadedly coupled together, as at 49, in axial extension of one another. The upper shaft section 47 is rotatably supported in bearings 50 and 51 and extends through a cap 52 threadedly plugged in an open end of the angle head. A terminal stem 53 of the lower drive shaft section 48 is received axially in a rear opening of the socket l7 and is releasably retained therein by means of a spring loaded latch pin 54.

The socket has a multi-sided recess 55 in its end which is adapted to engage over the nut 18. Above the socket recess is an elongated space 56 into which an end of the stud 19 may progress as the nut is tightened.

The drive shaft 16 defines a housing for the marking mechanism. Its interior provides a chamber 57 in which a hollow plunger 58 of the marking mechanism is reciprocable. A head 59 of a marking rod holder 61 is threadedly plugged in an open front end of the plunger. A reduced tubular portion 62 depends axially from the head with a slide fit through the stem 53 of the drive shaft and projects part way into the socket space 56 in axial alignment with the stud l9. Tube 62 is of lesser outer diameter than the stud. A spring loaded ball latch 63 cooperates with a flat 64 at the upper side of a cylindrical metal marking rod 65 to releasably retain the latter in the holder. The flat is longer in its longitudinal dimension than the diameter of the ball latch so as to permit limited axial movement or loss-motion of the marking rod relative to the holder. The transverse dimension of the flat corresponds substantially to that of the diameter of the ball latch. This arrangement, together with a slight looseness of the marking rod in the holder permits limited turning of the marking rod in the holder as well as limited side-to-side movement of the rod.

A piston 66 is pneumatically reciprocable in a piston cylinder 67 of the marking mechanism to repeatedly hammer an anvil 68 against the marking rod. Cylinder 67 is disposed within the interior of the plunger 58. A pin 69 anchored at its ends in the plunger extends, in order, through the upper end of cylinder 67 and through the head of a cylindrical guide rod 71 so that these connected elements move with the plunger as a unit. The guide rod 71 carries an O-ring seal 72 at its upper end. The cylinder has a peripheral land 73 between its ends which bears upon the inner wall of the plunger so as to define upper and lower annular clearances or chambers 74 and 75. An O-ring 76 in the land seals the clearances from one another.

The body of anvil 68 is slidable in the head 59 of the marking rod holder above the marking rod. In the raised position of the anvil, as in FIG. 3, an annular flange 77 at the base of its head 78 abuts against an open bottom end of the cylinder; and its head projects into the cylinder where it is subject to the pounding of the piston. An O-ring cushion 79 is provided for cushioning movement of the anvil. The marking rod has a dropped position wherein the upper shoulder of its flat 64 abuts the ball latch 63, and a pointed stylus end 80 of the marking rod projects slightly below the bottom of the holder tube 62, as appears in FIG. 1.

In the operation of the nutrunner, the socket 17 is applied to the nut 18 and the throttle valve 22 is depressed causing pneumatic operation of the motor 24. The torque of the motor is transmitted through the drive shaft 16 and the socket to tighten the nut upon the stud 19. At this time, inlet air is blocked by the open condition of the shutoff valve 23 and the unregistered condition of its ports from flowing through the hose line 45 to the marking mechanism 40. The marking mechanism at this time has, as in FIG. 1, an inactive condition wherein the plunger 58 is biased by its return spring 81 to an upper normal position in which a shoulder of the plunger abuts an internal shoulder 82 of the drive shaft, and its upper stem 83 is fully received in a complementary portion of the plunger chamber 57. In this inactive condition, the holding tube 62 and marking rod are held by the plunger clear of the work.

Upon delivery of final torque to the work and consequent moving of the shut-off valve 23 to closed condition, inlet air is shut-off from the motor and rotation of the drive shaft 16 stops. Inlet air is then diverted through the connected passages 41, 42 of the shut-off valve and valve bushing to the hose 45. The live air entering the angle head from hose 45 passes through a bore 84 in the drive shaft to a shallow inlet compartment 85 above the stem 83 of the plunger 59. Live air entering compartment 85 acts upon the plunger to force it gently downward against the resistance of its spring 81 until the open end of the holding tube 62 limits upon the top of the stud 19. As the marking rod 65 descends with the holding tube, it eventually engages the top of the stud and is then slidably retracted in the holder to take up the loss-motion permitted by the ball latch 63 and flat 64. The retracted movement of the marking rod raises the anvil so as to seat its flange 77 against the open end of the piston cylinder 67. The weight of the tool prevents the socket 17 from being forced free of the work in this action. As the inlet air is forcing the plunger downward, it also is flowing through a passage 86 to the interior area of the plunger defined by the upper clearance 74. The air then flows from clearance 74 through side ports 87 to an annular chamber 88 defined about the piston. Build-up of air in chamber 88 acts upon the piston to force it upwardly away from the anvil. In this movement, the piston slides over an enlarged diameter portion 89 of the guide rod 71 causing static air trapped in the space 91 above the piston to be compressed. The piston moves upwardly in this action until side ports 92 therein register with chamber 88. Inlet air entering chamber 88 then flows through the side ports 92 to the recessed interior 93 of the piston and acts to drive the piston forcefully downward against the anvil 68. Any static air trapped below the piston is forced in this action through side ports 94 and 95 in the piston cylinder to clearance 75. From the latter it flows through side ports 96 in the plunger to an annulus 97 communicating with vents 98. The compressed air trapped in the space 91 aids in forcing the piston downward. In its downward movement, the piston moves clear of the larger diameter portion 89 of the guide rod to develop a clearance 99 between its inner wall and a reduced end portion of the piston guide rod. This clearance allows static air trapped above the piston to escape through the ports 92 and 94 to the vents 98. The reciprocating cycle of the piston is automatically repeated as inlet air in chamber 88 again acts upon the piston to drive it upwardly, and it continues automatically to cycle at a high frequency until the operator releases the throttle valve to closed condition.

The plunger continues to be held downward with its tube 62 in contact with stud 19 during the entire time that the piston is reciprocating.

The stylus tip 80 of the marking rod is formed of hard metal such as carbide steel. It repeatedly marks or dents the surface of the stud 19 under a rapid succession of impacts imparted to the stud by the anvil. It is desired that the markings will not be one upon the other in a single spot but that multiple markings will be produced. To this end, the marking rod 65 has a loose fit in the holding head 59 and in the holding tube 62. Since there is a slight circumferential looseness at the upper end of the marking rod in the holding head, the marking rod tends to oscillate sideways in the tube 62 and to turn on its axis as it is subjected to repeated hammering by the piston. The tube serves to curb the extent of side-to-side swinging of the marking rod. This oscillating action causes a group of marks to be indented in the top of the stud 19 in a general circular pattern, as indicated at 100 in FIG. 4. There is also a slight looseness between the opposed ends of the anvil and the marking rod which permits the marking rod to rebound slightly following impact.

It is to be noted (FIG. 1) that the socket space 56 above the work is adequate to accommodate variations in the vertical extension of the work into the socket. It is also to be noted that the locating plunger 58 has the capacity to carry its holding tube 62 downwardly against the resistance of spring 81 until the holding tube has limited upon the work, regardless of the extent to which the work extends into the socket 17.

DESCRIPTION OF A SECOND EMBODIMENT In FIG. l, the marking mechanism is shown as combined with the angle head of a pneumatic nutrunner. In FIG. 5, the marking mechanism is shown as a separate unit, independent of the nutrunner. In this modified form, an inlet adapter section 102 has been threadedly coupled as at 103 to the upper section 47a of the units housing 16a. The lower section 48 of the housing carries the socket 17 which is adapted to receive the nut 18 and stud 19. The adapter 102 is provided with a throttle valve 105 and is connectible to a pressure air source by means of a feed line 104. In using this form, the socket is applied over work that has been previously torqued in order to center the work relative to the marking rod and holding tube; the throttle valve 105 is then actuated to effect operation of the marking mechanism and consequent repeated marking of the work.

In FIG. 1, the marking mechanism is shown as incorporated within the angle head section of the nut runner. However, as indicated in FIG. 5, the marking mecha nism may be a separate unit provided with its own housing. As such, it may be mounted in suitable manner as by bolting or clamping to the exterior surface of the nutrunner either at the rear of the angle head section or at some other selected area. When mounted as a separate unit, its inlet may be connected with the hose line 45; or it may be connected by the hoseline 104 with an independent source of operating air. Where the inlet is connected with the hoseline 45 of the nutrunner, the throttle valve 105 may be omitted.

As a separate unit, the marking mechanism may also be associated with various types of automatic machines. When so applied, its housing would be mounted I to a suitable work station and its mechanism caused to be operated at a precise time by means of suitable air flow controls operatively associated with the automatic machine. When so used, the socket element 17 may be used where the work is concerned with nutrunning; or the socket element may be omitted, when it is only required to mark the work, whatever it may be, to indicate that the work has passed through a final work stage.

It is understood where the marking mechanism is used as a separate unit that its housing may be designed, as needed, to facilitate its mounting or positioning.

I claim:

1. A pneumatic marking device for marking a piece of work, comprising a housing, a plunger within the housing carrying a marking rod for marking the work, a socket mounted to an end of the housing for receiving and centering the work for engagement by the marking rod, a return spring acting on the plunger normally biasing the plunger with the marking rod away from the work, the plunger being pneumatically operable against the bias of the spring to carry the marking rod into contact with the work, a piston pneumatically reciprocable within the plunger to pound the marking rod, and air control valve means having passage connections with both the plunger and the piston for feeding operating air concurrently to both the plunger and the piston, wherein the marking rod has a loss-motion connection with the plunger permitting limited axial and turning movement of the marking rod relative to the plunger; the loss-motion connection is in close proximity to an upper end of the marking rod and the major length of the marking rod projects beyond the point of the connection so as to allow side-to-side swinging of the marking rod; and a tube depends from the plunger in surrounding relation to and with some clearance relative to the marking rod, the tube providing a curb to the extent of side-to-side swinging of the marking rod.

2. A pneumatic marking device as in claim 1, wherein the tip of the marking rod normally depends from the bottom of the tube in such manner that when the plunger carries the marking rod into contact with the work the marking rod is caused to take up some of the loss-motion and retract axially into the tube until its tip obtains the level of the bottom of the tube.

3. A pneumatic marking device for marking a piece of work, comprising a housing, .a plunger within the housing carrying a marking rod for marking the work, a return spring acting on the plunger normally biasing the plunger with the marking rod away from the work, the plunger being pneumatically operable against the bias of the spring to carry the marking rod into contact with the work, a piston pneumatically reciprocable within the plunger to pound the marking rod, and live air inlet means having passage connections with both the plunger and the piston for conducting live air concurrently to both the plunger and the piston, wherein the marking rod has a loss-motion connection with the plunger permitting limited axial and turning movement of the marking rod relative to the plunger; the lossmotion connection is in close proximity to an upper end of the marking rod and the major length of the marking rod projects beyond the point of the connection so as to allow side-to-side swinging of the marking rod; and a tube depends from the plunger in surrounding relation to and with some clearance relative to the marking rod, the tube providing a curb to the extent of side-to-side swinging of the marking rod. 

1. A pneumatic marking device for marking a piece of work, comprising a housing, a plunger within the housing carrying a marking rod for marking the work, a socket mounted to an end of the housing for receiving and centering the work for engagement by the marking rod, a return spring acting on the plunger normally biasing the plunger with the marking rod away from the work, the plunger being pneumatically operable against the bias of the spring to carry the marking rod into contact with the work, a piston pneumatically reciprocable within the plunger to pound the marking rod, and air control valve means having passage connections with both the plunger and the piston for feeding operating air concurrently to both the plunger and the piston, wherein the marking rod has a loss-motion connection with the plunger permitting limited axial and turning movement of the marking rod relative to the plunger; the loss-motion connection is in close proximity to an upper end of the marking rod and the major length of the marking rod projects beyond the point of the connection so as to allow side-to-side swinging of the marking rod; and a tube depends from the plunger in surrounding relation to and with some clearance relative to the marking rod, the tube providing a curb to the extent of side-to-side swinging of the marking rod.
 2. A pneumatic marking device as in claim 1, wherein the tip of the marking rod normally depends from the bottom of the tube in such manner that when the plunger carries the marking rod into contact with the work the marking rod is caused to take up some of the loss-motion and retract axially into the tube until its tip oBtains the level of the bottom of the tube.
 3. A pneumatic marking device for marking a piece of work, comprising a housing, a plunger within the housing carrying a marking rod for marking the work, a return spring acting on the plunger normally biasing the plunger with the marking rod away from the work, the plunger being pneumatically operable against the bias of the spring to carry the marking rod into contact with the work, a piston pneumatically reciprocable within the plunger to pound the marking rod, and live air inlet means having passage connections with both the plunger and the piston for conducting live air concurrently to both the plunger and the piston, wherein the marking rod has a loss-motion connection with the plunger permitting limited axial and turning movement of the marking rod relative to the plunger; the loss-motion connection is in close proximity to an upper end of the marking rod and the major length of the marking rod projects beyond the point of the connection so as to allow side-to-side swinging of the marking rod; and a tube depends from the plunger in surrounding relation to and with some clearance relative to the marking rod, the tube providing a curb to the extent of side-to-side swinging of the marking rod. 